<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .row{
            display: flex;
            /* 行作为弹性容器 */
            flex-direction: column;
            align-items: center;
            justify-content: space-around;
            height: 500px;
        }
        .col{
            border: 1px solid indianred;  
            padding: 15px;
            background-color: aqua;
        }
    </style>
</head>
<body>
    <div class="row">
        <section class="col">3,good</section>
        <section class="col">3,good</section>
        <section class="col" style="flex: 2;">3,good</section>
        <section class="col" style="flex: 1;">3,good</section>
    </div>
    <!-- 让某个子元素占满容器flex1 -->
</body>
</html>